Pamplona, Spain: Thousands of revellers wearing red and white sprayed each other with red wine in Pamplona's main square on Wednesday for the start of Spain's famed San Fermin bull-running festival.

The nine-day fiesta got underway at midday to cries of "Viva San Fermin!" at city hall, followed seconds later by the firing of a firecracker known as the chupinazo.

Masses of merrymakers, many wearing traditional white outfits trimmed with red neckerchiefs and cummerbunds, danced and sprayed each other with cheap wine as red and white confetti rained down on them.

The crowds passed large yellow and black inflatable balls over their heads as scores looked down from packed apartment balconies.

The nine-day fiesta got underway at midday to cries of "Viva San Fermin!" at city hall, followed seconds later by the firing of a firecracker known as the chupinazo. AP.

For the first time this year the person who launched the chupinazo and set off the bedlam was chosen by a popular vote organised by city hall from a list of six candidates.

The winner was 85-year-old Jesus Ilundain Zaragueta.

The festival in honour of the patron saint of Spain's northern Navarra region — San Fermin — dates back to medieval times and combines religious processions, all-night partying and hair-raising daily bull runs.

Each day at 8 am, hundreds of people race with six huge bulls, charging along a winding, 846.6-metre (more than half a mile) course through narrow streets to the city's bull ring, where the animals are killed in an afternoon bullfight.

The bravest run as close to the tips of the horns as possible without being gored.

The first bull run, which traditionally draws the largest number of participants, is on Thursday. A run takes on average just under four minutes.

Fifteen people have been killed in the bull runs since modern day records started in 1911.

About 50 semi-naked animal rights activists daubed themselves with fake blood and stood outside of Pamplona's bullring on Tuesday holding signs that read: "Pamplona: Bloodbath for bulls" in several languages.

The festival was immortalised in Ernest Hemingway's 1926 novel The Sun Also Rises and it attracts thousands of visitors from around the world.

Hotel occupancy in Pamplona on the eve of the start of the festival stood at 80 percent, two percentage points higher than during the same time last year, according to the Navarra Hotel Association.

"I think the rise in the number of foreign visitors this year at the national level has had an impact on San Fermin," the association’s secretary general, Nacho Calvo, told AFP.

Pamplona city hall will spend 1.95 million euros ($2.17 million) on cultural programming during the festival which wraps on July 14. Over 400 events are planned, mostly concerts.

To stop revellers from relieving themselves in public during the festival, municipal workers this year coated the walls of busy areas of the city centre with a clear urine-repellent paint that causes pee to spray back on the person's shoes and pants.

Last year 76 people were fined in Pamplona, a city of around 300,000 people, for urinating in public during San Fermin. The offence carries a fine of 300 euros ($335) — or half that if it is paid right away.